Relative Humidity (RH) Sensor
Range: 0 to 100% RH, -40° to 70 °C exposure to conditions below -20°C (-4°F) or above 95% RH may temporarily increase the maximum RH sensor error by an additional 1%

Accuracy: ±2.5% from 10% to 90% (typical) to a maximum of ±3.5% including hysteresis at 25°C (77°F); below 10% RH and above 90% RH ±5% typical

Resolution: 0.01% RH

Drift: <1% per year typical

Response Time* Without Solar Radiation Shield: 30 seconds in air moving 1 m/sec

Response Time* With Solar Radiation Shield: 40 seconds in air moving 1 m/sec

Calculated Metrics: Vapor Pressure Deficit (VPD) in kPa, and Dew Point (computed from logged data)

Soil Moisture: Volumetric Water Content (VWC)
Measurement Range (select one at configuration)****
0.00 to 1.0 m³/m³ VWC in mineral soils
0.00 to 1.0 m³/m³ VWC in soilless media
Apparent Dielectric Permittivity: 1 (air) to 80 (water)

Accuracy:
±0.03 m³/m³ typical
±0.06 m³/m³ maximum
Apparent Dielectric Permittivity: ±1 Ɛa

Resolution:
0.001 m³/m³
Apparent Dielectric Permittivity: 0.002 Ɛa

Dielectric Measurement Frequency: 70 MHz

Volume of Influence: 1400 ml

Percent of Field Capacity (for VWC measurements only)
Range: 0 to 200%
Resolution: 0.1%

Soil Temperature*****
Measurement Range: -40 to 70°C (-40 to 158°F)

Accuracy:
±0.5°C from -40° to -20°C
±0.3°C from -20°C to 70°C

Resolution: 0.1°C (0.18°F)

Soil Bulk Electrical Conductivity (EC)
Measurement Range: 0 to 20000 µS cm-1

Accuracy:
±5 % from 0 to 10000 µS cm-1
±8 % from 10000 to 20000 µS cm-1

Resolution: 1 µS cm-1

Logger
Operating Range: -40 to 70°C (-40 to 158°F)

Radio Power: 1mW (0 dBm)

Transmission Range: Approximately 30.5 m (100 ft) line-of-sight

Wireless Data Standard: Bluetooth Low Energy (Bluetooth Smart)

Logging Rate: 1 second to 18 hours

Logging Modes: Fixed interval (normal, statistics) or burst

Memory Modes: Wrap when full or stop when full

Start Modes: Immediate, push button, date & time, or next interval

Stop Modes: When memory is full, push button, date & time, or after a set logging period

Time Accuracy: ±1 minute per month 0° to 50°C (32° to 122°F)

Battery Type: 2/3 AA 3.6 Volt lithium, user replaceable

Battery Life: 2 years, typical with logging interval of 1 minute and Bluetooth Always On enabled; 4 years, typical with logging interval of 1 minute and Bluetooth Always On disabled. Faster logging intervals and statistics sampling intervals, burst logging, remaining connected with the app, excessive downloads, and paging may impact battery life.

Memory: 195,000 measurements, maximum

Full Memory Download Time: Approximately 4-5 minutes; may take longer the further the device is from the logger

Dimensions:
Logger housing: 10.8 x 5.08 x 2.24 cm (4.25 x 2.0 x 0.88 in.)
Soil moisture sensor (only): 4.6 × 4.6 × 10.9 cm (1.81 × 1.81 × 4.31 in)
Soil moisture sensor needle length: 5.4 cm (2.14 in)
Soil moisture sensor needle diameter: 0.40 cm (0.16 in)
Sensor cable length: 2 m (6.56 ft)

Weight (Unpackaged):
263 g
9.3 oz
Weight (Packaged):
417 g
14.7 oz
Materials:
Acetal, silicone gasket, stainless steel screws
Soil Moisture Sensor: ASA plastic body with polyurethane epoxy filling and stainless-steel pins
Cable: PVC, UV resistant and rodent repellent (soil moisture sensor cable)

Environmental Rating:
Logger: NEMA 6 and IP67
Soil Moisture sensor and cable: xxxx

* Typical, up to 90% of change

** Per RH sensor manufacturer data sheet

*** Calibrated against an Eppley Precision Spectral Pyranometer (PSP) under natural daylight conditions. Absolute uncertainty under these conditions is ± 3% typical; ± 5% maximum.

**** The sensor data can be post-calibrated if necessary (e.g. the sensor is used in non-mineral soil types or higher than standard accuracy is required). Users can apply a calibration equation to the data exported from HOBOlink. The VWC range will depend on the calibration equation.

***** For additional accuracy, the sensor data can be post-calibrated for a particular soil by applying a calibration equation to the data exported from the app.